Charles a



(No Model.)

- 0. A. RANDALL.

Apparatus for Chemical.Telegramphls.

No. 238,713. Patented March 8,1881.

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ATTORN Y llwrruo STATES ATENT Quince.

CHARLES A. RANDALL, OF NEW YORK, N. Y.

APPARATUS FOR CHEMICAL TELEGRAPHS.

SPECIFICATION forming part of Letters Patent No. 238,713, dated March 8,1881.

Application filed J une 523, 1880. (No model.)

1' 0 all whom it may concern:

Be it known that I, CHARLES A. RANDALL, of the city, county, and StateofNew York, have invented certain new and useful Improvements in Systemsof Chemical Telegraphy and Apparatus therefor, of which the following isa specific'ation.

My invention relates to that class of chemical telegraphs in which thetransmission of signals is effected by means of anautomatically-operating transmitter, the movements of which arecontrolled by a previously-prepared pattern, usually consisting of aperforated or embossed strip, band, or sheet, the perforations orembossments upon which are so grouped as to produce the requiredduration and succession of signals upon the line.

In the chemical telegraphs heretofore in use, two principal modes oftransmission have been made use of, one of which-may be termed thesinglecurrent and the other the doublecurrent system. In thefirst-mentioned system the signals are formed by electrical currents orpulsations, all of which are of the same polarity, but of varyingduration or length, the spaces separating the signals from each otherbeing formed by breaking orintermitting the current. In the secondsystem the signals are formed by a succession of currents or impulsesalternately of positive and negative polarity. The latter system is muchthe most eifective, especially for very rapid transmission and on linesof considerable length, as the retarding and otherwise troublesomeeffects of static induction are greatly diminished by the well-knownaction of the alternating currents.

In order to transmit the required succession of alternating currents bymeans of a strip of perforated paper, which is the most usual andconvenient device for the purpose, it has heretofore been necessary toarrange the perforations in two rows or lines, one row of perforationstransmitting currents or impulses of one polarity, and the other rowthose of the opposite polarity. When this method is made use of there isnecessarily a break of the circuit at the transmitting contact-points ateach change of polarity. This interruption of the circuit produces aspark at the end of each signal, which has proved to be a very seriousobjection in practice, inasmuch as it frequently fuses the metalliccontact-points, and sometimes burns and destroys the edges of theperforations. The interruption of the circuit, also, has the effect oflessening or shortening the actual time during which the line is closedfor each signal, and this frequently causes single short impulses, ordots, as they are technically termed, to disappear or fail to berecorded at the receiving-station.

The usual method of recording which has been employed in connection withthe doublecurrent system hereinbefore referred to has been that ofcausing a strip of chemically-prepared paper to pass beneath twometallic recording-styluses placed side by side, these being soconnected with the circuit of the main line, that one stylus is made torecord only the positive currents from the transmitting-station, and theother stylus in like manner only the negative currents or impulses. Thusthe successive signals were recorded alternately in two parallel linesupon the strip of chemical paper. 'lheunequal consumption of the pointsof the styluses or pens, when of iron, and the frequent adjustment ofthem necessitated thereby, has always been a great and hithertoinsurmountableobjection to this method of recording.

It may also be remarked that the necessity of preparing thetransmitting-strip by perforating it with two rows of perforations addsgreatly to the complication of the perforating machinery which it isnecessary to make use of in the preparation of the strips, therebyrendering it much more expensive to construct and difficult to operate.

By the use of my improved method and apparatus I am enabled to make useof the double-current system of transmission, and at the same time toavoid in a great measure the difficultiesandobjections hereinbeforereferred to.

To this end my invention consists, first, in the combination of one ormore electro-magnets at the receiving-station, arranged to act upon apolarized armature, and a chemical recording apparatus in a secondarycircuit, which is opened and closed by the movement of said armature,with a pole-changing continuity-preserving key or transmitter at thesending-station, the movements of which are controlled by a suitablepattern strip, band, or sheet; second, in the combination of apatternstrip, band, or sheet, having predetermined characters formed thereon byperforating or embossing, with a pole-changing continuity-preserving keyor transmitter having contact-surfaces of graphite or carbon, wherebythe adjustment of the transmitter is more easily effected and theshort-circuiting of the battery is prevented.

In the accompanying drawings, Figure 1 is a side elevation of myimproved transmitter, and Fig. 2 represents a portion of a perforatedstrip or band whichis intended to be employed in connection therewith.Fig. 3 is a diagram of the receiving-instrument, and Fig. 4 is a portionof the record produced by the receiving-instrument, corresponding to theperforations in Fig. 2.

Referrin g to Fig. 1, A is the base, upon which the different parts ofthe transmitting apparatus are mounted. The standard B, attached to saidbase, carries a roller or drum, 0, upon the axis of which is a pulley,c, by which the drum may be put in rotation by a band, 0, attached toany convenient uniform source of power. In the drawings I have shown adriving-pulley, d, and crank 61, mounted upon a suitable standard, D,affixed to the base A. A strip of paper or other suitable material, E,which has previously been prepared, by means of perforations orotherwise, so as to form a prearranged pattern, is drawn over the drum Cas it revolves.

An L-shaped lever, F, is mounted upon an axis, 1), upon the standard G,and carries at the extremity of its shorter arm a roller, f, which restsupon' the pattern-strip E in the line of its perforations as it passesbeneath it. A spring, f, attached to the longer arm, keeps the roller fat all times pressed firmly against the pattern-strip. The effect ofthis arrangement is, that .when the successive perforations in thepattern-strip E (which are arranged in a straight line, as seen in Fig.2) pass beneath the roller f, a vibratory motion is communicated to thelever F as the roller drops into the perforations, and israised again adistance determined by the thickness of the hand during the passage ofthe spaces between the perforations. Thus the vibration of the lever Fcorresponds to the arrangement of the perforations in the pattern-stripE.

The long arm of the lever F carries a pair of contact-points, f,preferably of platinum, which play between the contact-surfaces i andThe latter are mounted upon spring-arms L and K, these being attached torigid arms L and K, pivoted at l and k upon separate standards H and G.The contacts t andjare to be carefully adjusted by means of the screws land It, provided for that purpose, so that when the long arm of thelever Fis at the middle point of its vibration the contactpoints f willbe pressed lightly by both contact-surfaces i and but the slightestmovement in either direction of the lever F will interrupt the contactupon the opposite side. The lever F is electrically connected with theline-wire through the standardB and binding-- screw 7). The contact 7'is connected, through the spring-arm K, standard G, and bindingscrew 9,with the positive pole of the main battery S. The contact 41 is in likemanner connected with the negative pole of the battery through L, H, andh. A wire running to the earth is attached to the battery S at a pointabout midway between its two poles, as shown in Fig. 1. Thus it will beunderstood that when the apparatus is in the position shown in Fig. 1,the roller f resting upon the pattern-strip E, the lever F will makecontact with the contact-surface z and a negative current will flow tothe line; but as the pattern-strip moves forward, the roller will dropinto each of the perforations e c as they successively pass beneath it,when the lever F will make contact with j at the same time or before itbreaks contact with 6. By this arrangement the circuit is neverabsolutely broken, but the current going to the line is changed frompositive to negative, or vice versa, at each movement of thecontact-lever F.

I prefer in all cases to make the contactsurfaces t' and j of graphite,carbon, or some similar semi-conducting material, thus availin g myselfof the well-known property of these substances, by virtue of which theirsurface conductivity varies enormously under pressure. By the movementof the lever F this pressure decreases upon one side as it increasesupon the other, the resistance being at a maximum upon both sides whenthelever is in its middle position and in contact with both sides, atwhich time the battery would be short-circuited were it not for thegreat resistance offered by the carbon contacts.

The receiving-instrument is very simple in its construction, and will beunderstood by reference to the diagram, Fig. 3. Apolarized armature, m,is mounted upon apivoted lever, m, preferably between the poles of twoelectro-magnets, M M. The lever m carries at its free end an adjustablemetallicstylus, n, which is suspended thereby above a strip ofchemically-prepared paper, 1). This strip of paper unwinds from aroll, 1) and is drawn along between rollers P P, (moved by clock-work orotherwise,) passing over a metallic roller, 0, beneath the stylus. Thepositive pole of a local battery, N, is attached to the lever m,carrying the stylus n, and the other pole is connected to the roller 0.A positive current traversing the line from the sending-station, andpassing through theelectro-magnets M M, will cause the polarizedarmature m to be de flected in a direction to bring the stylus n intocontact with the moving strip of chemical paper o, and a mark will beproduced thereby upon the paper, which will continue as long as thepositive current flows over the line. The negative or spacing currentwill act in the opposite direction upon the polarized armature m,withdrawing the stylus from the paper. The marks thus correspond inlength to the groups of perforations in the pattern-strip, as will beobserved by comparing Figs. 2 and 4. The dashes or long marks in therecord are produced by means of two perforations in a group placed closetogether one after the other. In this case the space between theperforations is of such short duration that the rever sal of the currentproduced therebyis not perceptible upon the record at thereceiving-station. Two circular perforations are employed in lieu of asingle elongated one, for reasons connected with the mechanicalconstruction of the perforating machinery, and which need not be furtherenlarged upon in this description.

I do not desire to restrict myself to the use of a pattern strip or bandhaving the characters perforated therein as described, although I preferthat arrangement on account of its convenience and economy. A sheet maybe used adapted to be placed upon a cylinder with the charactersarranged thereon in a spiral. These characters may be embossed upon thestrip or sheet instead of being perforated.

' I would also remark that a chemical recordin g -instrument of theordinary description, known under the general name of a Bain recorder,may be placed directly in the main circuit at the receiving-station, andthe electro-magnets, armature, and secondary battery dispensed with,although I consider this arran gement much less advantageous for generalpurposes than that which I have described.

I claim as my invention-- 1. The combination, substantially ashereinbefore set forth, of one or more electro-magnets at thereceiving-station, acting upon a polarized armature, and a chemicalrecording apparatus in a secondary circuit, which is opened and closedby the movements of said CHARLES A. RANDALL. Witnesses:

N ELSON ZABRISKIE, FRANK L. POPE.

7 armature, with a pole-chan gin g continuity-pre-

